High frequency sonic transducers



13, 1964 J. w. MCAULEY HIGH FREQUENCY SONIC TRANSDUCERS Filed April 13,1959 QIVENCTOR. BY 900120]. flGMfJWG Qe ATTORNEYS Fig.8

3,145,312 Patented Aug. 18, 1964 3,145,312 HIGH FREQUENCY SONlCTRANSDUtIERS James W. McAuley, Toledo, ()hio, assignor to Libby-Owens-Ford Glass Company, Toledo, Ohio, :1 corporation of Ohio FiiedApr. 13, 1359, Ser. No. 806,152 7 Claims. (Cl. 310-26) The presentinvention relates broadly to high frequency sound generating transducersand more particularly to improvements in the energy directing meansforming a part of said transducers as employed in treating surfaces.

For example, the cleaning and surfacing of glass sheets has beenaccomplished by the utilization of high frequency sound energy. Thus, ina cleaning operation the surface of a glass sheet to be cleaned iscovered with a liquid conducting medium consisting of water, or waterplus an additive, and sonic energy is applied to the medium to causecavitation therein which results in a thorough cleaning of the glass.For surfacing, the conducting medium is provided with an abrasivematerial which on cavitation in the medium is caused to bombard theglass surface and to remove portions thereof.

Sound energy generating apparatus for accomplishing such cleaning andsurfacing operations must produce relatively high power level outputs,which darnands that transducers for providing the energy have arelatively high efliciency and be of a rugged construction. Otherfeatures that are required in such transducers are that they can bereplaced individually, that they can be maintained in any preferredorientation without a substantial diminution of operating efficiency orpower output level, that they be reasonably inexpensive, and that theybe easily adaptable for effective use within a relatively wide band offrequencies of excitation voltage.

Perhaps the best sound generating transducers for glass cleaning andsurfacing operations are magnetostrictive transducers provided with ametallic energy directive means firmly attached to the magnetostrictiveelement or core.

Originally such energy directive means were solid bodies of metal,dimensioned to be mechanically resonant at the operating frequency ofthe transducer.

' However, it was soon found that in order to be satisfactory for theirintended purpose such solid bodies had to be formed,'machined orotherwise shaped in a particular way and, as so shaped, came to becommonly known as horns. But, even with this special shaping, the solidhorn was not fully effective for underwater applications such as thesurface treating uses described above.

Subsequently, in United States Patent No. 2,723,386, issued November 8,1955, to Leon W. Camp, it was proposed to use a plurality of small legs,extending in parallel relation from the electro mechanical vibrator andconnected at their outer ends to a unitary diaphragm, as the horn orenergy directive means.

In this arrangement, however, each of the individual legs making up thehorn had to be specially and accurately shaped so that, while improvedresults were obtained, the cost of producing the horns was even higherthan before.

Still later a so-called hollow horn was proposed as a means ofincreasing the effectiveness of such transducers. Again, while thismodified construction gave somewhat improved results it still furtherincreased the already almost prohibitive cost of the horns because itadded new problems in the way of shaping and accurate machining and itwas still considered necessary to provide such hollow horns with legs,in the form of reinforced wall portions extending in the direction ofvibratory energy transfer, as a means of suppressing spurious lateralvibrations that might damage the directive means and/ or change thenatural frequency of the transducer with a resultant lowering ofoptional efficiency.

Further, it was thought heretofore that all of these specially shaped,energy directive means had to be constructed of a relatively expensive,high corrosion-resistant, diflicult to machine stainless steel. Thecasting and machining of such energy directive means is a considerableportion of the total labor cost of a transducer and, as indicated above,prior to the present invention, the production of such energy directingmeans was extremely time-consuming and approached the prohibitive incost.

This invention is based on applicants discovery of a novel type ofhollow, vibratory energy directing member for use with sound generatingtransducers that is readily obtainable, that can be constructed ofrelatively inexpensive and easy to work materials, and that requires nospecial subsequent shaping procedure.

Briefly stated, the horn of the present invention is of multipiececonstruction embodying a cylindrical or tubular extension member thatwill give results that are equal, if not superior, to the resultsobtained with the complicatedly shaped difficult to produce prior knownstructures.

In the drawings, wherein like numerals are employed to designate likeparts throughout the same:

FIG. 1 is a perspective view, partially in section, of the completenovel vibration directing means of the invention assembled into amagnetostrictive sonic energy generating transducer device; and

FIG. 2 is an exploded perspective view of the energy directing means ofFIG. 1.

With reference now to the drawings and particularly to FIG. 1 there isshown a high frequency sound generating transducer of the type withwhich the present invention is particularly concerned. This transducercomprises a core 10, an energizing coil 11 in surrounding relationshipto said core, and a special energy directive means 12 mounted in fixedcontacting relationship with a vibrating portion of the core.

As shown, the core ltl consists of a plurality of U- shaped laminationsof a magnetostrictive material such as nickel placed in a facecontacting relationship forming a unitary structure. It is essentialthat the laminations be maintained in this close contacting relationshipin order to provide a stable operation, which may be accomplished eitherby a mechanical means such as the clip 13 or by bonding the corelamination together in a plastic or resinous material.

The coil 11 consists of a plurality of turns of wire inductively woundon the two legs of the core. Additionally, a polarizing means is usuallyprovided which can be, for example, either a second coil wound on thecore for passing a direct current therethrough or, as shown in FIG. 1, apermanent magnet 14 located between the two legs of the core.Energization of the coil 11 with a suitable high frequency voltagesource (not shown) causes a cyclic increase or decrease in the length ofthe legs of the core 10 which provides a source of vibratory energy, orvibrating surface, at the lower or cross bar portion of the core. Thedirecting and amplifying means 12 in a completed unit is affixed to thislower vibrating surface of the core by silver soldering, brazing,welding or other similar means.

Although for puropses of illustration the core 10 is shown to becomposed of laminated sheets of ferromagnetic material it is consideredthat the novel directive means of the invention would be equallyapplicable for use with a sound generating core composed of amagnetostrictive ceramic, a piezoelectric crystal, or any otherconventionaltype of vibratory energy source.

The novel vibratory energy directive means 12 of the invention comprisesthree main parts, namely, an upper portion 15, a central extensionmember 16, and a lower energy distributing portion or operating member17. These three individual units are integrally combined in a way whichwill be set forth below to form a superior sonic energy directive andamplifying device the purpose of which is to transfer and amplify thevibratory energy generated by the core to a point where it can be usedto perform useful work.

In a preferred construction, the upper portion 15 consists of a castmetal base member having a circular flat face 18 which in the completedtransducer is Welded or otherwise fixedly secured to the lower surfaceof the cross arm of the core 10. There is also provided a cylindricalplug 19, integral with the body member and having a diameter less thanthat of the face 18, that extends in a direction substantially 90 to theflat face of the body member. The plug 19 may be either solid orpartially hollowed out so as to enlarge the central cavity within thecompleted directing means as shown in FIGS. 1 and 2. Although it is wellknown that the provision of a cavity within a vibratory energy directivemeans produces an amplification of the vibratory energy, the use of asolid plug rather than a hollowed out one does not cause a diminution ofthe total amplifying effect afforded by the cavity, of'such a magnitudeas to preclude its use. It is, therefore, considered within thecontemplation of the invention to use an upper portion 15 having a plug19 consisting either of a solid or hollowed out cylinder.

The upper portion 15 is also provided with a first cylindrical portion20 concentric with the plug 19 and having a diameter slightly largerthan the plug, and a second cylindrical portion 21 concentric with andhaving a diameter slightly larger than the portion 20. The purpose ofthese cylindrical portions will be brought out in detail below.

The extension member or horn 16 comprises essentially an elongatedcylindrical metal tube the ends of which are finished off in planesperpendicular to the long dimension of the member. The inner diameter ofthe member is of such a dimension as to permit it to receive the plug 19therein in a closely fitting relationship.

Contrary to conventional opinion which is that the energy directivemember must be made entirely of stainless steel applicant has found thatthe extension member 16 may be made of any of a large number ofdifferent metals having reasonable strength and resistance. For example,metals which have been found to be fully satisfactory in this regard arealuminum, copper, bronze, and brass.

The lower portion 17 preferably consists of a metallic base portionhaving a flat substantially rectangular surface 22 tapering to a shortcylindrical portion 23 rising from the rectangular surface in a normaldirection and having an opening therein of sufficient diameter to allowit to receive the extension member in a tightly fitting manner. Althoughthe energy distributing portion may be composed of the same metalslisted above with regard to the extension member 16, the flat workingsurface 22 may be provided with a hard metal wearplate (not shown)firmly attached thereto and completely covering the rectangular faceportion.

The different parts of the multipiece energy directive means 12 can bejoined to one another by brazing, silversoldering or welding, but it isthe concept of the invention that an organic epoxy resin cement, such asEpon 6 or 8, is preferable. Not only is the use of such an adhesivematerial relatively inexpensive and easier to apply than theabove-mentioned alternative methods, but the completed unit can bedisassembled easily without damaging the different component parts.Thus, if it is desired to take the directive means 12 apart this may bedone by placing the unit in a furnace and subjecting it to a temperatureof aproximately 300 F. for several minutes which will cause the organiccement holding the parts together to disintegrate releasing them whileleaving the individual parts of the transducer undamaged.

It is to be noted that when the upper portion 15 is assembled to theextension member 16 the shoulder of the cylindrical portion 20 rests onthe upper end of member 16, and that the peripheral surface of theportion 20 is recessed below the outer surface of the member 16. Whenthe completed transducer is mounted for operation a sealing gasket, suchas an O-ring, is received in this recess and forced against the shoulderof cylindrical portion 21 to provide a liquid-proof seal preventing theaccess of the energy conducting liquid to the electrical part of thetransducer. 7

The novel construction of the energy directive means set forth hereinhas several important advantages over the' conventional known structuresof the same general type.

Thus, as was brought out above, whereas it was previously considerednecessary to construct an energy directing member with speciallyreinforced portions, or legs, the directive member of the invention haseliminated the legs and in so doing has overcome the problem ofdiflicult forming techniques and the need for difficult and expensivemachining afterward.

Also, as was noted before, it was previously thought to be necessary toconstruct the complete directive members of relatively expensive highcorrosion-resistant stainless steels which are diflicult to cast andmachine. However, it has been found in the special multipiececonstruction of this invention that the central extension member 16 andthe lower member 17 can be made from certain relatively inexpensiveeasily obtainable metals rather than stainless steels.

A further advantage to be obtained by the novel construction of theinvention is that it possesses a flexibility that permits the productionof units which may be quickly and easily adapted to use with excitationvoltages over a relatively wide range of frequencies. By way ofexplanation, vibratory energy directing members must have a preciseoverall length. That is, a precise dimension measured along the line ofvibratory energy transmission, which dimension is directly dependentupon and determined by the frequency of the excitation voltage of thetransducer. It has been found that even a slight variation in thisdimension from the optimum results in a sharp drop in performance. Theprior art structures discussed above were constructed for a particularvoltage frequency and could be varied only a very slight amount bymachining one end so as to reduce the length. However, in the directivemember of the invention the lower iember' 17 and the upper portion 15that is secured to the core may be combined with central extensionmembers of various lengths to provide completed transducers for use witha variety of different excitation voltage frequencies. Summing this upin different Words, Whereas in the prior art each transducer was madefor use with a particular voltage frequency, the invention makes itpossible to provide transducers for use with a relatively wide band ofinput voltage frequencies by merely cutting the cylindrical extensionmembers to predetermined lengths and asembling them with the same lowermembers and upper portions.

A still further advantage of the invention is that which results fromthe use of a non-metallic adhesive material to join the individual partsto form the completed directive member rather than brazing or weldingthem together. With such a construction if the operating face 22 becomesworn or damaged the lower member 17 can be removed relatively easily anda new one cemented in place. This of course, would not be possible withthe prior devices discussed above since their Welded unitaryconstruction does not permit such partihl replacement and insteadrequires that the whole device, frequently including the laminated coreand coil, be discarded in case of damage to any part thereof. On theother hand, with this invention both the extension member and the lowermember may be removed and new ones substituted without the laminatedcore or the coil windings being injured.

It is to be understood that the forms of the invention disclosed hereinare to be taken as the preferred embodiment thereof, and that variouschanges in the shape, size and arrangement of parts may be resorted toWithout departing from the spirit of the invention or the scope of thefollowing claims.

I claim:

1. A sound energy directing and amplifying means for use in amagnetostrictive sound generating transducer, comprising a metallic bodymember for attachment to a vibrating magnetrostrictive body and having aplug-like portion integral with said body member extending therefrom, ahollow cylindrical extension member having an opening therein forreceiving the plug portion of the contacting member in one end thereof,a second body member provided with a circular opening for receiving theother end of the extension member therein and having an outersubstantially fiat operating face normal to the long dimension of saidextension member, and adhesive bodies securing said metallic body memberto said extension member and said extension member to said second bodymember.

2. An energy directing and amplifying means as claimed in claim 1,wherein said extension member and said operating portion are composed ofa non-ferrous metal.

3. An energy directing and amplifying means as claimed in claim 1,wherein said adhesive bodies are composed of epoxy resins.

4. A high frequency sonic transducer, comprising a laminated core ofmagnetostrictive metal, a coil for energizing said core, a metallic bodymember welded to said core, having a cylindrical plug portion extendingtherefrom along the line of major magnetostrictive movement, a hollowmetallic cylinder having the planes of its ends normal to the centerline of the cylinder the internal opening of which is so dimensioned asto receive the end of the cylindrical plug therein in a tight fittingrelationship, a second body member having an opening therein forreceiving the other end of the extension member therein, andnon-metallic adhesive means for securing the cylinder to the cylindricalplug and also to the second body member in a tightly sealed unitaryrelationship.

5. A sound energy transducer, comprising a hollow cylindrical metaltubular member of substantially uniform diameter throughout its lengthand open at its opposite ends, a first metallic body member having aflat outer face and a plug-like portion fitting within and closing oneend of said tubular member, a second metallic body member having anopening for receiving the other end of the tubular member therein andprovided with an outwardly directed flat operating face closing theadjacent end of the tubular member, means for detachably securing thefirst and second body members to the tubular member, and a vibrationgenerating core rigidly secured to the outer face of the first bodymember.

6. A sound energy transducer as claimed in claim 5, in which the meansfor detachably securing the first and second body members to oppositeends of said tubular member comprises a heat softenable resinousadhesive.

7. A sound energy transducer, comprising an elongated tubular metalmember having a cylindrical wall of substantially uniform diameterthroughout its length, said cylindrical Wall defining a cylindricalpassageway of substantially uniform diameter throughout the lengththereof and open at its opposite ends, a first metalliic body memberhaving a fiat outer face and a plug-like portion projecting into saidpassageway and closing one end thereof, a second metallic body memberhaving an opening for receiving the other end of said tubular member andprovided with an outwardly directed flat operating face closing theadjacent end of said tubular member, means for detachably securing thefirst and second body members to said tubular member, and a vibrationgenerating core rigidly secured to the face of said first body member.

References Cited in the file of this patent UNITED STATES PATENTS1,380,869 Fay June 7, 1921 2,498,990 Fryklund Feb. 28, 1950 2,748,298Dalosi May 29, 1956 2,779,695 Brown Jan. 29, 1957 2,930,913 Camp et a1Mar. 29, 1960 2,946,981 ONeill July 26, 1960 2,956,789 Rich Oct. 18,1960

1. A SOUND ENERGY DIRECTING AND AMPLIFYING MEANS FOR USE IN AMAGNETOSTRICTIVE SOUND GENERATING TRANSDUCER, COMPRISING A METALLIC BODYMEMBER FOR ATTACHMENT TO A VIBRATING MAGNETROSTRICTIVE BODY AND HAVING APLUG-LIKE PORTION INTEGRAL WITH SAID BODY MEMBER EXTENDING THEREFROM, AHOLLOW CYLINDRICAL EXTENSION MEMBER HAVING AN OPENING THEREIN FORRECEIVING THE PLUG PORTION OF THE CONTACTING MEMBER IN ONE END THEREOF,A SECOND BODY MEMBER PROVIDED WITH A CIRCULAR OPENING FOR RECEIVING THEOTHER END OF THE EXTENSION MEMBER THEREIN AND HAVING AN OUTERSUBSTANTIALLY FLAT OPERATING FACE NORMAL TO THE LONG DIMENSION OF SAIDEXTENSION MEMBER, AND ADHESIVE BODIES SECURING SAID METALLIC BODY MEMBERTO SAID EXTENSION MEMBER AND SAID EXTENSION MEMBER TO SAID SECOND BODYMEMBER.